Narrative:

Start and taxi out were normal. We were cleared to taxi to runway 25L at las. As we approached the departure end, there were 2 aircraft ahead of us. One was in position and rolled as we were about 2000 ft from the end. A company aircraft went into position at that time. I then pushed the flight attendant call button and after a somewhat longer than usual time, got a response from the flight attendants and called for the before takeoff checklist. As we were completing the checklist, company rolled on takeoff and I went around the corner and into position. After we were on the runway, my first officer asked if we were cleared on the runway (he later told me this was because his lights were not on). After takeoff, we got a message from center to call las. When we landed, I made the call and the tower controller said he had checked the tapes and we were never cleared onto the runway. Obviously both my first officer and I feel that we were cleared into position and hold. The only rationale I can think of for our actions is that we are still not completely comfortable with the new procedures. In the past, we would do the 'below the line' items only when cleared onto the runway. Doing these items conferred a tacit confirmation that the clearance had been given. I believe that in this case, doing essentially the same checklist convinced us that we had in fact been cleared.

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Original NASA ASRS Text

Title: A B737-500 FLT CREW THOUGHT THEY WERE CLRED INTO POS AND HOLD WHEN THEY WERE NOT AT LAS, NV.

Narrative: START AND TAXI OUT WERE NORMAL. WE WERE CLRED TO TAXI TO RWY 25L AT LAS. AS WE APCHED THE DEP END, THERE WERE 2 ACFT AHEAD OF US. ONE WAS IN POS AND ROLLED AS WE WERE ABOUT 2000 FT FROM THE END. A COMPANY ACFT WENT INTO POS AT THAT TIME. I THEN PUSHED THE FLT ATTENDANT CALL BUTTON AND AFTER A SOMEWHAT LONGER THAN USUAL TIME, GOT A RESPONSE FROM THE FLT ATTENDANTS AND CALLED FOR THE BEFORE TKOF CHKLIST. AS WE WERE COMPLETING THE CHKLIST, COMPANY ROLLED ON TKOF AND I WENT AROUND THE CORNER AND INTO POS. AFTER WE WERE ON THE RWY, MY FO ASKED IF WE WERE CLRED ON THE RWY (HE LATER TOLD ME THIS WAS BECAUSE HIS LIGHTS WERE NOT ON). AFTER TKOF, WE GOT A MESSAGE FROM CTR TO CALL LAS. WHEN WE LANDED, I MADE THE CALL AND THE TWR CTLR SAID HE HAD CHKED THE TAPES AND WE WERE NEVER CLRED ONTO THE RWY. OBVIOUSLY BOTH MY FO AND I FEEL THAT WE WERE CLRED INTO POS AND HOLD. THE ONLY RATIONALE I CAN THINK OF FOR OUR ACTIONS IS THAT WE ARE STILL NOT COMPLETELY COMFORTABLE WITH THE NEW PROCS. IN THE PAST, WE WOULD DO THE 'BELOW THE LINE' ITEMS ONLY WHEN CLRED ONTO THE RWY. DOING THESE ITEMS CONFERRED A TACIT CONFIRMATION THAT THE CLRNC HAD BEEN GIVEN. I BELIEVE THAT IN THIS CASE, DOING ESSENTIALLY THE SAME CHKLIST CONVINCED US THAT WE HAD IN FACT BEEN CLRED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.